Community Forums

WesPearson · 07-15-2015, 10:27 PM

HR Endeavor 1998 38 ft DP Cummins 6.7 275 hp Allison trans. On a 5000 mi trip last October pulling a Honda Fit from OC, CA thur Denver to MS to North Texas, Big Bend, El Paso back to OC. Averaged 10.4 MPG. I try to keep it at 62 mph. I have a VMSPC running on my laptop on the dash. It lets you manage your driving to get the best speed, power and miliage. Best investment I ever made on the coach. Wouldn't leave home without it.

WesPearson · 07-15-2015, 10:29 PM

Make that a 5.9 Cummins in my Evdeavor.

Ramets · 07-17-2015, 06:50 AM

You certainly don't buy one of these traveling earthquakes for the mpg. In over 5yrs. of full timing I've only checked my mpg once, and that was a trip to Alaska. We went almost a total of 10,000 miles, and it came out to be 9.75mpg towing our Saturn Vue for our Cummins ISC. Otherwise it is what it is.

bobkathy95 · 09-26-2015, 07:48 AM

I know this thread is old - but the topic is not. I have a 2013 Cummins 6.7 @360 hp in my RV. I have been unable to locate any tuners for the later model engines. Banks does not offer anything. Is it because Cummins has already maxed out the 6.7 ??
I am not going to race my DP - I would just like to get better mileage. Any suggestions? (other than modify the length of my right leg) LOL
I currently get 9 to 10 mpg cruising at 65 with the Allison 3000 tranny.

ChasA · 09-26-2015, 08:15 AM

Bobcat,
One solution: SLOW DOWN. Chasing mpg by trying to mod your engine is fruitless.

halftimer · 09-26-2015, 08:26 AM

Quote:

Originally Posted by KC

Hello all, looking for some Real world MPG on any class A using a Cummins 6.7 motor. With and without towed.

Thanks

KC

gas mileage is how far you can go on a tank of fuel if you want more mileage put in a bigger tank.

Steve Ownby · 09-26-2015, 08:29 AM

Quote:

Originally Posted by ChasA

Bobcat,
One solution: SLOW DOWN. Chasing mpg by trying to mod your engine is fruitless.

ChasA is 100% correct. Your best opportunity for increasing economy is speed and driving technique.

You should use an rpm target of 100-200 rpm above your max torque. The ISB Max torque is at 1600-1800 rpm depending on engine rating. Usually what ever speed will enable you to maintain top gear over small grades and interstate overpasses will be best. Coasting when you can & avoid heavy braking or heavy throttle.

Steve Ownby
Full time since '07

Paramedic 1 · 09-26-2015, 08:43 AM

I "push" our 2000 Allegro Bus down the highway at around 55 to 58. I know I am not making a lot of traveling friends but I have found with my diesel running around 1500 rpm in 6th gear we seem to get the best mileage.
JMHO....We totally enjoy the trip and are a little sad when we arrive as we love the changing scenery.
I am in total agreement to slowing down to help with mpg and this thing is a barge and NOT meant to get very good mpg.
Also if you are driving into a hard headwind or crosswind it is almost better to pull over for the day...otherwise your mpg WILL suffer greatly!
We are happily retired and are in NO hurry....not like when we were younger...lol.....happy trails and stay safe

jondrew55 · 09-26-2015, 08:52 AM

My computer on the Excursion says I'm getting about 10 on average. I'm always running the generator in the summer so there's another 1/2 to 1 gallon per hour. The only reason I'd care about MPG is if my fuel consumption drastically got worse indicating some sort of mechanical issue. Other than that I couldn't care less. Fuel cost is the least significant cost contributor to me. If (when) diesel went back to $5 a gallon it would still not significantly change my RV use.

On a 5000 mile trip you're using about 500 gallons of diesel. Today that's about $1200. If the price doubles, would you stop using your MH?

Ross Koile · 09-26-2015, 10:00 AM

I have an Itasca Ellipse (42 ft, 8.9 L Cummins, 36,000 lbs) and I routinely get 11 mpg (highway only) on level roads at 55 mph. It drops about 1/2 mpg if I get into rolling hills like what is found in the Florida panhandle. In city traffic (which I avoid whenever possible) the best I can do is 7 - 8 mpg and sometimes worse. These numbers are from the Freightliner computer.

Steve Ownby · 09-26-2015, 10:39 AM

Quote:

Originally Posted by Ross Koile

I have an Itasca Ellipse (42 ft, 8.9 L Cummins, 36,000 lbs) and I routinely get 11 mpg (highway only) on level roads at 55 mph. It drops about 1/2 mpg if I get into rolling hills like what is found in the Florida panhandle. In city traffic (which I avoid whenever possible) the best I can do is 7 - 8 mpg and sometimes worse. These numbers are from the Freightliner computer.

I'm guessing your Freightliner computer is optimistic. If it's important to you to have a handle on your mpg, you'll have to record all fuel used for at least 5,000 miles. If you run your generator you will have to estimate fuel usage. I'm guessing about 1/2 gal per hour would be a fair estimate. Also AquaHot if you have it.

If you do those things l'm guessing your Cummins fuel economy will end up in the 8-9 mpg if you are a conservative driver.

If your Freightliner computer allows an adjustment for "tire revolutions per mile", check that against your tire makers value.

Steve Ownby
Full time since '07

MSHappyCampers · 09-26-2015, 10:58 AM

I get 8 MPG average on a Cummins ISC350 pulling a Honda CRV, driving 60 MPH. The coach weighs about 33,000 lbs.

Agaveguy · 09-26-2015, 11:22 PM

The trip computer on our 40' ISB 360 says 10.9.

When we first took possession of it, it said 11.4. We try to drive 60-65 and accelerate at a modest rate. We're not in a hurry to get where we're going.

Ross Koile · 09-27-2015, 12:25 AM

Quote:

Originally Posted by Steve Ownby

I'm guessing your Freightliner computer is optimistic. If it's important to you to have a handle on your mpg, you'll have to record all fuel used for at least 5,000 miles. If you run your generator you will have to estimate fuel usage. I'm guessing about 1/2 gal per hour would be a fair estimate. Also AquaHot if you have it.

If you do those things l'm guessing your Cummins fuel economy will end up in the 8-9 mpg if you are a conservative driver.

If your Freightliner computer allows an adjustment for "tire revolutions per mile", check that against your tire makers value.

Steve Ownby
Full time since '07

Surely you are not suggesting that any device put on any coach by either Freightliner or Winnebago is other than perfect - are you?.

The odometer vs gallons pumped seems to support the Freightliner computer. This is strictly highway mileage - not city plus highway. One curious thing about this is that before the coach had 3500 miles on it, this kind of fuel economy did not happen. By the way I am not pulling anything, I am not running the generator, and I seem to be the slowest thing on the road. Engine is turning 1490 rpm which is close to the top of the torque curve. This coach is not maxed out on weight. Tire pressure is 115 - 120 psi as per Winnebago placard. When I get into a head wind, the mileage suffers. Last run was between Hammond, Louisiana and Baytown, Texas on I-12/I-10 with no reported wind above 3 mph in any direction.